Enumerating DGN Models or Cells

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Q MicroStation DGN files contain one or more models that store model geometry and other information. When you are creating a model, you often place a cell to copy frequently-used geometry into the drawing. Cells are stored in a cell library file. A DGN file always contains at least one model; a cell library usually contains many models, each of which is a cell.

• How do I find the models in a DGN file?
• How do I list the cells in a cell library?
• How do I find the range of a DGN model?

A Similar questions are posted now and then on the Bentley Discussion Groups. A cell library is just a MicroStation DGN file having a .cel extension. A cell is a model, and a model is a cell. Iterating the cells in a cell library is identical to iterating the models in a design file.

Remember the mantra: A model is a cell. A cell is a model. Raise your understanding to a higher plane: mumble this mantra every morning!

There is sample code for VBA developers and MDL wonks.

Enumerating with MicroStation VBA

Here's a simple VBA example that illustrates how to obtain information about models (in a DGN file) or cells (in a cell library). Since a cell library is a DGN file, this code works for either. Copy this code into a regular VBA module, then run it within the IDE, or from a MicroStation keyin vba run modMain.Main …

Option Explicit
Option Base 0

' ---------------------------------------------------------------------
Sub Main()
    Dim nModels   As Long
    nModels = EnumerateModels(ActiveDesignFile)
    MsgBox "Found " & CStr(nModels) & " models ", vbInformation Or vbOKOnly, "Enumerated Models"
End Sub

' ---------------------------------------------------------------------
Function EnumerateModels(dgn As DesignFile) As Integer
    Dim index As Integer
    Dim strName As String
    For index = dgn.Models.count To 1 Step -1
        Dim oModel As ModelReference
        Set oModel = dgn.Models(index)
        Debug.Print "Model [" & CStr(index) & "] '" & oModel.name & "'"
    Next
    EnumerateModels = dgn.Models.count
End Function

When you run the above code, the name of each model or cell is displayed in the IDE's immediate window. You will see the following information dialog that tells you the number of models found …

Enumerating with MDL

Here's an MDL example of cell iteration, courtesy of Mark Anderson at Bentley Systems …

void  cellIterator (void)
{
  DgnIndexIteratorP pDgnIndexIterator = NULL;
  DgnFileObjP       pLibObj           = NULL;
  DgnIndexItemP     pDgnIndexItem     = NULL;
  //	Get the current attached library
  int               iStatus           = mdlCell_getLibraryObject (&pLibObj, tcb->celfilenm, TRUE);

  pDgnIndexIterator = mdlModelIterator_create (pLibObj);
  mdlModelIterator_setAcceptCellsOnly (pDgnIndexIterator, TRUE);

  while (pDgnIndexItem = mdlModelIterator_getNext (pDgnIndexIterator))
  {
    mdlModelItem_getName (pDgnIndexItem, wCellName, MAX_CELLNAME_LENGTH);
    mdlModelItem_getDescription (pDgnIndexItem, wCellDescription, MAX_CELLDSCR_LENGTH);
    mdlModelItem_getData (pDgnIndexItem, &cellType, &isThreeD, &isLocked, &isHidden, &lastSaved);
  }

  mdlModelIterator_free (pDgnIndexIterator);
}

Q How do I find the range of a DGN model?

A Similar questions are posted now and then on the MicroStation Programming Forum. MicroStation models contain graphic elements (VBA Element). Each graphic element has a range, or extent. In VBA the extent is a Range user defined type (UDT), with High and Low components. The extent of a DGN model is the union of all element extents, and is available as the ModelReference.Range property.

The following VBA procedure displays the active model's range …

' ---------------------------------------------------------------------
'   Display the max and min values of the range of all elements in a model
' ---------------------------------------------------------------------
Public Sub GetModelRange()
    Dim oModel                              As ModelReference
    Set oModel = ActiveModelReference
    Dim range                               As Range3d
    Const IncludeAttachments                As Boolean = True
    Const IgnoreAttachments                 As Boolean = False
    range = oModel.range(IgnoreAttachments)
    Dim max                                 As String
    Dim min                                 As String
    If (oModel.Is3D) Then
        max = "Model " & oModel.name & " range maximum: " & CStr(range.High.X) & "," & CStr(range.High.Y) & "," & CStr(range.High.Z)
        min = "Model " & oModel.name & " range minimum: " & CStr(range.Low.X) & "," & CStr(range.Low.Y) & "," & CStr(range.Low.Z)
    Else
        max = "Model " & oModel.name & " range maximum: " & CStr(range.High.X) & "," & CStr(range.High.Y)
        min = "Model " & oModel.name & " range minimum: " & CStr(range.Low.X) & "," & CStr(range.Low.Y)
    End If
    ShowMessage max, max, msdMessageCenterPriorityInfo
    ShowMessage min, min, msdMessageCenterPriorityInfo
End Sub

Convert Range to Visible Shape

If you want to visualise the range found with the above code then you need to create a rectangle using a ShapeElement. A ShapeElement requires an array of Point3d vertices, so we need to convert the Range3d …

' ---------------------------------------------------------------------
'   Display range of all elements in a model as a rectangle
' ---------------------------------------------------------------------
Public Sub GetModelRangeAsRectangle()
    Dim oModel                              As ModelReference
    Set oModel = ActiveModelReference
    Dim range                               As Range3d
    Const IncludeAttachments                As Boolean = False
    range = oModel.range(IncludeAttachments)
    Dim vertices(0 To 4)                    As Point3d
    Dim i                                   As Integer
    '  First and last vertices of a shape must be coincident
    For i = 0 To 4
    	vertices(i) = range.Low
    Next i
    vertices(1).X = range.High.X
    vertices(2).X = range.High.X
    vertices(2).Y = range.High.Y
    vertices(3).Y = range.High.Y
    Dim oRectangle                          As ShapeElement
    Set oRectangle = CreateShapeElement (Nothing, vertices)
    ActiveModelReference.AddElement oRectangle
    oRectangle.Redraw
End Sub